Datatsushi is an extraterrestrial creature in Forbidden Siren, unintentionally setting in motion the game's events, acting as the major influence in the game's storyline. Crash-landing on planet Earth, he was killed when the people of Hanuda suffered a famine and ate him in the belief that he is a gift from the Gods. In his death, he cursed Hisako Yao, who would then spent countless centuries trying to resurrect him, and erected the Mana religion in his honour.
AppearanceEditDatatsushi appears in Hanuda in 684 as a lengthy, albino worm creature, with a slicked appearance to its flesh. Its arms were short and almost in a state of atrophy, while its head hosted a large mouth and small indentations which appear to be eyes.
Later on in the game, its spiritual form was summoned, which appears similar to its corporeal appearance, save for the fact that its lower portion has sprouted tendrils, and its flesh has become frayed slightly and hanged off its arms, which have also lengthened. It also appears covered in flickering white flame, possibly due to the fact that it is incomplete.
Once Hisako Yao offered her own life to Datatsushi in the Inferno, Datatsushi takes on a new form that strongly resembles his description in Hanuda legend: It had three insect-like abdomens, with an adjoining thorax and wings. The top half of its body resembles a fish with insect eyes and antennae, and it also has a probiscus.
Datatsushi arrives in Hanuda in 684 AD, when it fell from a comet that passed the Earth every 333 years. It lands in Hanuda on a rock formation (the Mana Stone) that happens to be in the shape of a Mana Cross. There it lays dormant until villagers happen upon it, and due to extreme starvation, devour it.
Following his disastrous landing in 684 AD, Datatsushi is devoured by the earliest Hanuda residents, being mistaken for a fish since it is in a helpless, maggot-like immature state at that time. In its last breath, it cursed the starving villagers, killing everyone but a young pregnant Hisako. She is immediately rendered immortal, under Datatsushi's influence, and sought to forever repent for her sins by summoning Datatsushi back to life in the future.
With the Mana religion, Hisako uses ceremonies that center around using any of her descendants with psychic powers as the "Bride of God", sacrificing them so that their blood can resurrect the worshipped alien. One such ritual in 1976 involving the Miyako Kajiro of that year fails, resulting in the town being buried in a landslide when Datatsushi screams (the sound of a siren). Part of 1976 Hanuda is pulled into an alternate dimension.
In 2003, another ritual is used, this time with another descendant named Miyako Kajiro. However, Kyoya Suda, who is visiting the town, accidentally interrupts the ritual, causing it to fail as well. Like before, the 2003 version of the town is sent into an alternate reality (the otherworld).
In the alternate reality, the water has been replaced by a similar red substance, which allows people to turn into Shibito. There is nothing beyond the island, as a red ocean consumes anything past it, ensuring that no one can leave. The Shibito are loyal to Datatsushi, and whenever his scream, the siren, is heard, they bathed in the red water so that they can evolve and become closer to their god. The red water also allows the Shibito to sightjack each other, due to Datatsushi's insect traits that ends up creating a hive mind between him and his followers.
Hisako, having remembered what she is supposed to do, found a head washed up along the shore of the town. She sees a white-haired version of herself, smiling in satisfaction. The head is actually that of Datatsushi, sent from the future. With this head, Hisako can use it as the template from which Datatsushi can rise from when Miyako is used as part of the ritual.
Eventually, Hisako Yao is able to capture Miyako and manages to pull off a successful ritual, resulting in Datatsushi resurrected. Unfortunately, Datatsushi's state is an incorporeal ghost-like being, as unexpectedly, Miyako sent some of her blood in Kyoya, whose blood has also transfered into Shiro Miyata. Datatsushi becomes unhinged, rampaging across the Nest, where the deity is supposed to be housed. During this rampage, he sends Kyoya, Kei Makino and Tamon Takeuchi down further to the bottom of the Nest. He interrupts Tamon and Yoriko's reunion, but sunlight leaks through and burns his ghostly body. Using his dimension-bending abilities, he is able to send himself in Inferno, which houses the comet he arrived to Earth in.
Hisako arrives in the Inferno tending to her master. Now in a small, sickened, physical body, he is helpless when Kyoya Suda enters the realm in order to finish off the alien and end the nightmare over Hanuda. Jun Kajiro, who is then a Shibito, faces off against Kyoya to protect his leader. During this, the Uryen is activated through Miyako's blood, and is used to kill Jun. Hisako, in a last bid, offers her strength to Datatsushi so that he can defend himself. The offer works, restoring the god to full strength. Despite this, Kyoya uses the Uryen to burn Datatsushi, and, armed with Jun's family blade the Homuranagi, decapitating him.
Datatsushi's head rolls towards Hisako, who then ages to an advanced age with the death of her god ending the curse, and she falls into a vortex in time and space. However, this is not the end of Datatsushi and his faithful servant. The old Hisako, Datatsushi and a box containing the head float down a river and were sighted by the people of Hanuda in the past, leading to a myth involving them. Further along time, the white-haired Hisako appears to her younger self and gives her Datatsushi's head, thus allowing him to be resurrected in the first place, creating a time loop in which Datatsushi's past and future are eternally tied.
- Curses Hisako Yao, who becomes a follower of his; resurrects him; gives him strength in Inferno; makes sure his existence is kept in a loop
- The 1976 and 2003 Miyako Kajiros involved with rituals used to resurrect him
- Jun Kajiro protects him in Inferno
- Resurrection witnesses by Kyoya Suda; killed by him in Inferno
- Kei Makino follower of Mana religion; witnesses his rebirth
- Tamon Takeuchi knew of resurrection ritual; unable to stop his rebirth and is sended down into the Nest's lower levels by Datatsushi; almost attacked by the god
- Yoriko Anno witnesses resurrection; nearly killed by him
- Datatsushi's entire role in filled in by Kaiko in Siren: Blood Curse. With the exception of a name change and different appearance, Kaiko serves as that game's version of the character with no traits from other characters in the original game, unlike the other characters in Blood Curse.
- Datatsushi (and by extension, Kaiko in the remake) is unrelated to Mother and Otoshigo, despite all three bearing the following similaraties:
- Being able to create alternate realities (Mother)
- Involved with shibito (Otoshigo)
- Screams resembling a wailing siren (Mother)
- Ironically, while Datatsushi is seen by the Mana religion, specifically Hisako, as a god, Mother and Otoshigo are beings that are closer to resembling a deity than himself, as they were made from the darkness left over when Annuko (God) created light and can only be killed by being impaled by his remains.
- Datatsushi is the only otherworldly main antagonist who has a movie stage that is as the very start of a game's Link Navigator, as well as the only main antagonist in general to have an unlockable scene.
- Datatsushi's movie stage is glimpsed at by Miyako in her movie where she is being prepared for the ritual in Day 2. In it, she sees visions of the villagers in 684AD eating Datatsushi.
- Datatsushi's movie stage serves as the basis for one of the traditions in the Siren franchise; additional movies that are unlocked after the player collects all 100 Archives. Yoriko Anno also has a movie stage which is unlocked through the collection of Archives.